Permanent magnet brushless dc motors are widely used in a variety of applications due to their simplicity of design, high efficiency, and low noise. These motors operate by electronic commutation of stator windings rather than the conventional mechanical commutation accomplished by the pressing engagement of brushes against a rotating commutator. To achieve electronic commutation, brushless dc motor designs usually include an electronic controller for controlling the excitation of the stator winding(s). Advantageously, electronic commutation allows for specific, user-controlled motor operating characteristics.
Given the relative simplicity of design for permanent magnet brushless dc motors, however, prior art designs have failed to satisfactorily achieve a reliable design which may be produced at a minimized cost. For example, prior art brushless dc motor designs generally control motor operating characteristics using relatively complicated microprocessor-based electronics. Incorporation of a microprocessor into the control board is expensive and time-consuming from a production standpoint. In addition, the more components that are incorporated into the control electronics, the more likely it is that operational malfunctions will occur as a result of damaged or improperly installed electronics.
Also, elaborate mounting mechanisms have been developed in the prior art for mounting hall effect sensors adjacent the rotor to sense rotor rotational position. The hall effect sensors are typically connected to the control board via separate wires to provide a feedback signal for controlling motor operation through the electronics. Typically, the electronics are also mounted to the assembly using a separate bracket or other mechanism which further complicates and adds costs to the production process.
Accordingly, there is a long-felt need in the art for a brushless dc motor which is capable of achieving user-controlled operating characteristics, and which is efficient, compact, and cost-effective.